MONTAUK residents are up in arms and ready to fight real estate developer Peter Kalikow for access to a private beach he bought and closed to the public.

Kalikow, the former MTA chairman who once owned this newspaper and still owns 45 Ferraris, bought the 2.2 acres of beach, dunes and wetland in October 2007 for $2.5 million, the East Hampton Press reports.

While the previous owners had always allowed people to use the beach for swimming and sunbathing, Kalikow, whose 16,000- square-foot mansion is next door on 12 acres, posted “No Trespassing” signs.

Julie Brumm, an organizer of the Committee to Save the Star Island Cove Beach, said the former owners were so carefree about sharing that most residents thought East Hampton Town already owned the property.

“People are upset,” Brumm said. “This is a bad precedent for the whole town. We don’t need more rich people taking beaches away in East Hampton. The town board needs to look at this.” Neighbors are also wondering why the beach wasn’t on the town’s Community Preservation Fund acquisition list.

At a debate of candidates for town supervisor last week, Democrat Ben Zwirn insisted the town could buy the beach. “Peter Kalikow is not the easiest guy in the world to get along with, but we can gang up on him,” Zwirn said.

But Kalikow’s spokesman, Marty McLaughlin, told Page Six the developer plans to build a house on the property for his two children and has applied to erect a fence to prevent trespassing. “The fact is, it’s private property,” McLaughlin said. “If anyone got hurt there or drowned, he could be responsible.”

Kalikow once fought an eight-year battle against environmentalists and the federal government when he applied to build a 425-foot dock for his 137-foot yacht. He now has a smaller boat, and a smaller dock.